Customer lost color coding and the categories were not all listed any more

Patrick Doman
Patrick Doman used Ask the Experts™
I had this question after viewing Missing Categories and colors in Outlook &

I was reviewing the above article because it is similar in nature to a event that a customer of mine is experiencing.
Outlook 2016, Office 365, Categories got reset to different colors and some were deselected from being shown.

I ran outlook.exe /remigratecategories.
That worked to bring them back, but the colors were wrong and certain categories were not selected any more to be shown.

Does anyone know what causes Office 365 / Outlook 2016 to lose these? Was it a update I ran? was it corruption of some sort?
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Last Knight
Distinguished Expert 2018
Hi Patrick,

I'd first check in OWA to see if it was a local OST corruption. If the categories & colors were in the OWA that points to a local issue with the OST file. Since Office 365, I have not seen this issue because they made it part of the mailbox so it syncs from the servers opposed to living/dying on the local Outlook installation as it used to. Recreate the OST file and it should resolve your issue.

Let me know if you have any other questions!
Patrick DomanCTO / President


I did delete the OST and I let the mailbox regenerate the local cache.
When we did this and got back in to the outlook client, the categories were fixed.
Blue Street TechLast Knight
Distinguished Expert 2018

Glad I could help...thanks for the points!

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